How to enable debugging log level in postfix?

■ Requirement : enable debugging in postfix
■ OS Environment : Linux[RHEL, Centos]
■ Application: postfix
■ Implementation Steps : 

1. Add the following lines in /etc/postfix/main.cf file ::

debug_peer_list = example.com
debug_peer_level = 2

NOTE: Here example.com is the domain for which log messages will be displayed.

2. enable -v -v in master.cf file(/etc/postfix/master.cf) like :

smtp unix - - n - - smtp -v -v
smtp inet n - n - - smtpd -v -v

3. Restart postfix. check /var/log/maillog :

$ service postfix restart
$ tailf /var/log/maillog